From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EBC628C864; Wed, 28 Jan 2026 02:25:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769567158; cv=none; b=QICzE5U/m3nzDcL2YAF+YcMfpLUsWRhQs7WfrxtWew682LruUXvYIgFD+IE7b1hUBcBubWb2Yi5jKeo9HUXeJwLEqry+85hX/WY2CtmIsX0nMGAk9InVQdMdpFbgj/RxJwghVv99dt3RBrNB0Wb2pQqRV/2A90g6eB6huVorQ8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769567158; c=relaxed/simple; bh=1fMfmkSAk2FmGtHJNUwOGGC3405qV/fBN6ZwGBNp60A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HiXNMP7udGuYmYgcN1C4bfX2qPOtWoQrqlxy/5EWbo3HskQRpmAx+yy/lGfCC1gFvuuYiqbiifBO+3G/Tbl+yMD0q2HtBXGe2J0Xl9ckc9EkMMaHOW8HXhOMNtEEkWPDHW3RjJ5TOyE4wdTRg/9oSnp1vbdbqGvo4gcGsvgmN+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bU+7UPiQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bU+7UPiQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 321C6C116C6; Wed, 28 Jan 2026 02:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769567158; bh=1fMfmkSAk2FmGtHJNUwOGGC3405qV/fBN6ZwGBNp60A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bU+7UPiQao2Uv+KInv+Huemi8CQCdoEi3gTJNXH/8bNhnAEKTirqHbgS8pLRFIKMS VXebTqtj8c5B25y1BO1y9l97mL7hpz/4gaZDvqTuBGbPP39JXwGbI4BztjdXFRk5Bs bJgDELrDuzfn4mOhes927UBeueifCUxLw2KWOIQYbRLFE4fI//ctySSp6YYQ8N4n5n MQqfbmI4m+o7/zJSgkoKmEbVqaUhek7W6BM3cG5/qMAezhtxCb3KQM9UVVGicqWiYI OeBgO+BEqymmNv9lqZ7LMjEv6b1QoWRPf0+R4fhKEzTUlEuWeHW9C8OSzJNVn+7Spq FFaKY7NfPLdlg== From: Jakub Kicinski To: lukasz.majewski@mailbox.org Cc: Jakub Kicinski , festevam@gmail.com, linux-arm-kernel@lists.infradead.org, s.hauer@pengutronix.de, kernel@pengutronix.de, horms@kernel.org, shawnguo@kernel.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org, conor+dt@kernel.org, devicetree@vger.kernel.org, wahrenst@gmx.net, pabeni@redhat.com, davem@davemloft.net, netdev@vger.kernel.org, richardcochran@gmail.com, edumazet@google.com, andrew+netdev@lunn.ch, robh@kernel.org, krzk+dt@kernel.org, andrew@lunn.ch Subject: Re: [net-next,v20,3/7] net: mtip: Add buffers management functions to the L2 switch driver Date: Tue, 27 Jan 2026 18:25:54 -0800 Message-ID: <20260128022554.4151421-1-kuba@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260126103400.1683125-4-lukasz.majewski@mailbox.org> References: <20260126103400.1683125-4-lukasz.majewski@mailbox.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- net: mtip: Add buffers management functions to the L2 switch driver This patch adds buffer management functions for the MTIP L2 switch driver, implementing mtip_free_buffers(), mtip_create_page_pool(), and mtip_alloc_buffers() for RX page pool and TX bounce buffer handling. > diff --git a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c > index 03c5163d6508..9c21a3d29c1c 100644 > --- a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c > +++ b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c > @@ -888,11 +888,96 @@ static void mtip_get_drvinfo(struct net_device *dev, > > static void mtip_free_buffers(struct net_device *dev) > { > + struct mtip_ndev_priv *priv = netdev_priv(dev); > + struct switch_enet_private *fep = priv->fep; > + int i; > + > + for (i = 0; i < RX_RING_SIZE; i++) { > + page_pool_put_full_page(fep->page_pool, > + fep->page[i], false); Can fep->page[i] be NULL here? When mtip_alloc_buffers() fails partway through the RX allocation loop, it calls mtip_free_buffers() via the error path. At that point, only some fep->page[] entries have been allocated - the rest remain NULL from the kzalloc initialization. The call chain page_pool_put_full_page()->page_pool_put_netmem()-> page_pool_unref_and_test()->page_pool_unref_netmem()-> netmem_get_pp_ref_count_ref() will attempt to access &NULL->pp_ref_count when passed a NULL page, causing a NULL pointer dereference. Should there be a NULL check before calling page_pool_put_full_page()? > + fep->page[i] = NULL; > + } > + > + page_pool_destroy(fep->page_pool); > + fep->page_pool = NULL; > + > + for (i = 0; i < TX_RING_SIZE; i++) > + kfree(fep->tx_bounce[i]); > } [ ... ] > +static int mtip_alloc_buffers(struct net_device *dev) > +{ > + struct mtip_ndev_priv *priv = netdev_priv(dev); > + struct switch_enet_private *fep = priv->fep; > + struct cbd_t *bdp; > + struct page *page; > + int i, ret; > + > + ret = mtip_create_page_pool(fep, RX_RING_SIZE); > + if (ret < 0) { > + dev_err(&fep->pdev->dev, "Failed to create page pool\n"); > + return ret; > + } > + > + bdp = fep->rx_bd_base; > + for (i = 0; i < RX_RING_SIZE; i++) { > + page = page_pool_dev_alloc_pages(fep->page_pool); > + if (!page) { > + dev_err(&fep->pdev->dev, > + "Failed to allocate page for rx buffer\n"); > + goto err; > + } [ ... ] > + err: > + mtip_free_buffers(dev); When this error path is taken, fep->page[] may contain NULL entries for pages that were never allocated. > + return -ENOMEM; > }